Vol. 81 No: 6

Title:
Effects of auxins on organogenesis and somatic embryogenesis from juvenile explants of Eucalyptus erythronema, E. stricklandii, and two inter-specific hybrids

Authors:
PAULINE GLOCKE, GRAHAM COLLINS and MARGARETY SEDGLEY

pp: 1009-1014

Abstract:
Organogenesis and somatic embryogenesis were investigated in apex and cotyledon explants of Eucalyptus erythronema, E. stricklandii and their inter-specific hybrids Eucalyptus erythronema E. stricklandii cv. ´Urrbrae Gem` and ´Hybrid 2.5`, following exposure to 1 mg 1^-1 naphthaleneacetic acid (NAA) plus 1 mg 1^-1 2,4- dichlorophenoxyacetic acid (2,4-D), or 3, 5 or 15 mg 1^-1 NAA alone. Somatic embryogenesis was not observed macroscopically; however, structures characteristic of globular somatic embryos or root primordia were observed using light microscopy of apex explants of ´Urrbrae Gem` seedlings after 14 d on Murashige and Skoog (1962) (MS) medium supplemented with 3 mg 1^-1 NAA. Root development was associated with explant vascular tissue and observed in all plant growth regulator (PGR) treatments, but was less on explants treated with 1 mg 1^-1 NAA plus 1 mg 1^-1 2,4-D than in all NAA-alone treatments. Shoot development was observed on apex explants after sub-culture on PGR-free medium, but was less after treatment with 1 mg 1^-1 NAA plus 1 mg 1^-1 2,4-D compared to all NAA-only treatments. Roots and shoots developed simultaneously on apex explants after culture for 1 week on MS medium supplemented with 15 mg 1^-1 NAA.

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